<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>伪类选择器</title>
    <style>
        /* 伪类选择器是状态：hover 鼠标经过（悬停） */
       a{
        color: #333;
        text-decoration: none;
       }
       /* 标签名：hover 鼠标经过这个标签的时候状态会变成什么样子 */
       a:hover{
        color: red;
        text-decoration: underline;
       }
       p{
           width: 100px;
           height: 100px;
           background-color: pink;
       }
       p:hover{
        background-color: hotpink;
       }
       .box{
        width: 100px;
        height: 100px;
        background-color: pink;
       }
       .box:hover{
        background-color: deeppink;
        color: #fff;
        width: 200px;
       }

    </style>
</head>
<body>
    <a href="#">百度一下</a>
    <p></p>
    <div class="box">我是盒子</div>
</body>
</html>